Researchers turn wastewater into “inexhaustible” source of hydrogen


September 19, 2011

Penn State researchers have developed an electrolysis cell with RED stack that produces pure hydrogen from waste water (Image: U.S. Fish & Wildlife Service)

Penn State researchers have developed an electrolysis cell with RED stack that produces pure hydrogen from waste water (Image: U.S. Fish & Wildlife Service)

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Currently, the world economy and western society in general runs on fossil fuels. We've known for some time that this reliance on finite resources that are polluting the planet is unsustainable in the long term. This has led to the search for alternatives and hydrogen is one of the leading contenders. One of the problems is that hydrogen is an energy carrier, rather than an energy source. Pure hydrogen doesn't occur naturally and it takes energy - usually generated by fossil fuels - to manufacture it. Now researchers at Pennsylvania State University have developed a way to produce hydrogen that uses no grid electricity and is carbon neutral and could be used anyplace that there is wastewater near sea water.

The researchers' work revolves around microbial electrolysis cells (MECs) - a technology related to microbial fuel cells (MFCs), which produce an electric current from the microbial decomposition of organic compounds. MECs partially reverse this process to generate hydrogen (or methane) from organic material but they require the some electrical input to do so.

Instead of relying on the grid to provide the electricity required for their MECs, Bruce E. Logan, Kappe Professor of Environmental Engineering, and postdoctoral fellow Younggy Kim, turned to reverse-electrodialysis (RED). We've previously looked at efforts to use RED to generate electricity using salt water from the North Sea and fresh water from the Rhine and the Penn State team's work follows the same principle - extracting energy from the ionic differences between salt water and fresh water.

A RED stack consists of alternating positive and negative ion exchange membranes, with each RED contributing additively to the electrical output. Logan says that using RED stacks to generate electricity has been proposed before but, because they are trying to drive an unfavorable reaction, many membrane pairs are required. To split water into hydrogen and oxygen using RED technology requires 1.8 volts, which would require about 25 pairs of membranes, resulting in increased pumping resistance.

But by combining RED technology with exoelectrogenic bacteria - bacteria that consume organic material and produce an electric current - the researchers were able to reduce the number of RED stacks required to five membrane pairs.

Previous work with MECs showed that, by themselves, they could produce about 0.3 volts of electricity, but not the 0.414 volts needed to generate hydrogen in these fuel cells. Adding less than 0.2 volts of outside electricity released the hydrogen. Now, by incorporating 11 membranes - five membrane pairs that produce about 0.5 volts - the cells produce hydrogen.

"The added voltage that we need is a lot less than the 1.8 volts necessary to hydrolyze water," said Logan. "Biodegradable liquids and cellulose waste are abundant and with no energy in and hydrogen out we can get rid of wastewater and by-products. This could be an inexhaustible source of energy."

While Logan and Kim used platinum as the catalyst on the cathode in their initial experiments, subsequent experimentation showed that a non-precious metal catalyst, molybdenum sulfide, had 51 percent energy efficiency.

The Penn State researchers say their results, which are published in the Sept. 19 issue of the Proceedings of the National Academy of Sciences, "show that pure hydrogen gas can efficiently be produced from virtually limitless supplies of seawater and river water and biodegradable organic matter."

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

Annoter step to true clean energy. Well done. P

Patrick Luppi

So exciting!


Im afraid Im something of a cynic, I gotta feeling this will be the last time we see anything more about this.


Let us hope that this technique proves to be scalable and inexpensive, so that it can soon begin to be applied to the mountains of waste we produce....



THIS IS GREAT! Funny part is that when I was a school boy (early sixties), I imagined such a system to produce a breathable oxygen/hydrogen to be used for scuba diving.. Of course, I had (and still have not) any idea if the mixture is breathable, but had concerns about having H2 and O together, thinking they might explode spontaneously... I had found out about \"concentration electric batteries\" from the French \"Science et Vie\"...

Andrei Badescu

It seems jackmeister, that you were right. I couldn\'t find any mention of this in the Proceedings of the National Academy of Sciences publication (dated 19th September!). It\'s already gone!


Mark Hutchinson

Interesting - long distance liveaboard, cruising or racing sailors could provide a stream of \'technology demonstrators\'. The organic waste produced by people living aboard a boat, plus the salt water environment would require just a little fresh water - stored or caught in rainfall/dew - as inputs.

Less waste dumped in the seas, less fossil fuel consumed on the boats ( many thousands of these ) and hydrogen for power and light...?

I\'d like to see it.


Interesting research and apparently with almost unimaginable potential. The questions that are not answered by this article are: (1) Is it scalable (2) How long is it likely to be before this technology could be applied on a commercial level?

Incidentally, what is the relevance of Image No 3?


\"While Logan and Kim used platinum as the catalyst on the cathode in their initial experiments, subsequent experimentation showed that a non-precious metal catalyst, molybdenum sulfide, had 51 percent energy efficiency.\"

Does this mean that molybdenum sulfide makes just 51% of what platinum makes or is it something different altogether?

Renārs Grebežs

Breakthrough?? Doubtful that it will happen large-scale, cuz of my new \'Anderson\'s Rule\' : \"It takes 100+ alleged \'breakthroughs\' to have one real product come to market\"


I doubt this system would produces more usable energy than using microorganisums that produce methane when they digest the waste material, and feed the electricity generated by the RED process into the grid.

Methane is a better motor fuel than hydrogen anyway.


@Mark Hutchinson You must be looking in the wrong spot here is the link, try the search tool next time, it works wonders.

Peter Mason

Interesting ...

Imagine floating hydrogen generation barges anchored in any number of estuaries around the world. Collecting sea water and fresh water from the river/sea boundary areas, and discharging process effluent into river output.


So you could end up running a car off your own shi err waste??

Bet this tech gets buried or sabotaged. too dangerous if it is real. Hmm don\'t you need sea water.. damn I live inland.

Maybe this could be the trigger for large environmental projects that create pipes that pump sea water into inland lagoons where water is allowed to evaporate and is used to \'clean\' waste water producing H2 for fuel, salt for industry.

the start of proper environmental egineering

Hmm maybe I need to cut back.. on day dreaming

Karsten Evans

Great in the lab, where you can take out the membranes and replace them easily. Not so good in the real world. If they could get it down to something simple, like a waterfall with several pools of water with some kind of catalyst or bacterial colony, then they have something.


Also ... when you generate electricity from the hydrogen, you get pure clean water in that process. All good.

William Volk

so much little time. Simple answer, reduce energy consumption.

Grant Ertel
This is an interesting process but I have serious doubts. We can easily generate methane in huge quantities and we don\'t. And that is an absurdly simply process. Common sense tells me that we could actually use easily available methane to run engines to push generators to get hydrogen if we wished and since the methane is essentially free we need not be concerned with fuel costs to feed the engines if for some reason we just must have hydrogen. And if this process simply needs a bit of electricity to produce hydrogen solar cells or a windmill can provide the small amount of power required. Perhaps I lack depth of understanding but it seems to me that this research is interesting but not exactly something that will ever be used for hydrogen production. I hope I am wrong. Jim Sadler

Hydrogen storage is still a problem. It is too bulky, requiring liquidation, and that takes energy. When storage is cheap, fuel cells will rule.


The ionic membranes are $$$, prone to biofouling and hopefully will be made from recyclable bio-plastics not petro-plastics. California does not permit stand-alone sea water intakes for desalination plants (impingement & entrainment issues) and desal plants have to couple with power plants who are exempt from intake permits (which can take 18 months +) and estuaries will probably take longer.

Coastal Marine

Fear not Mark H. The story is still available at the PoNSA here

Corinne Civish

Okay so let me get this straight... We take the hydrogen out of water using dirty water, electricity and special bacteria. We then use the hydrogen in a fuel cell to create water again and gain some electrons back. What the heck!? Why even mess with hydrogen? Use the specially grown bacteria and the dirty water/ freshwater mixture to create electricity, then put it into a battery or into the grid. Don\'t mess with the freaking hydrogen, the more conversions it goes through the less efficient it is. Their catalyst has 51% efficiency, that means 49% of the energy is wasted whereas if the power went straight into a wire or a battery you would get darn near 100% efficiency. There is nothing revolutionary about this. Hydrogen sucks.


This reads like a godsend. But can it be ramped-up? For instance, if it takes too much space to create it is not much good. An example, California\'s base load electricity could be created with a solar array that is 120 miles square, and that is not feasible.


Journalists SHOULD link to the ACTUAL ARTICLE, not to the home page of yesterdays announcements.

Anyway - I found it - but it\'s a subscription based read.

Hydrogen production from inexhaustible supplies of fresh and salt water using microbial reverse-electrodialysis electrolysis cells PNAS 2011 ; published ahead of print September 19, 2011,

Mr Stiffy

How many times do we have to see an item on electrolysis to know it works, we know it works, there\'s nothing to research there, if its the new battery that is the news they are reporting on the wrong headline. We already know that hydrogen is infinite, look at the sun.

So get on with it society is saying, get it into homes, businesses and cars.

Gavin Greaves

i agree with jackmeister. plus i don\'t think the oil companies will be jumping for joy on this one,unless they can get their finger in the pie!!

Facebook User

Too many times we focas on ONE green project and claim it to be the savior of mankind. Yet we rarely combine existing techniques for grater efficiency. waste heat is a common byproduct for several processes, but we seldom use it. Sterling engines, steam and those chips that convert heat into electricity (can\'t remember the name) all run off heat and could be used togeather. Heat is a major byproduct of solar, in fact it is a problem for solar. Put the chips on the back of the solae cells as a heatsink and improve the solar output as well as convert the heat directly into electricity by way of the chips!. Use Solar waste heat as a preheater for steam or hot water tanks, The asians are more effecient than we are. Example are the piazo crystal power towers. piazo crystals produce power as long as the wind makes them move (from any direction) and also work a pump under ground. when the wind fails, fluid pumped by the tower falls through waterwheels to produce power when it is at rest.


This would be a great source of energy for seasteads, and might even become commercially available by the time the first seastead will be launched. Probably the Blueseed shipstead won\'t be able to benefit from this though.

Dan Dascalescu

Hydrogen storage is not a problem, very safe and inexpensive. It has been done for years using metal hydride. Hydrogen is not stored in the metal hydride in gaseous form, but is absorbed into the material's crystal structure. The energy densities that can be achieved using metal hydride are very large. Another advantage of using metal hydride is the low storage pressure, just 2-4 bars depending on temperature and the amount of hydrogen that the storage unit contains. As storage units do not suffer from self-discharge, they can be stored for years without any loss of capacity. Since only hydrogen is stored in the metal hydride, the gas drawn from storage units is very pure, approximately 99.9999%. Portable hydrogen storage units are well suited to use with fuel cells and other applications that require a source of hydrogen. 1Kg of hydrogen will generate 32.7 kWh with only water and heat as a byproduct. (background Automotive Design Engineer)

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